Storage area networks (SANs) are typically implemented to interconnect data storage devices and data servers or hosts, using network switches to provide interconnectivity across the SAN. SANs may be complex systems with many interconnected computers, switches, and storage devices. The switches are typically configured into a switch fabric, and the hosts and storage devices connected to the switch fabric through ports of the network switches that comprise the switch fabric. Most commonly, Fibre Channel (FC) protocols are used for data communication across the switch fabric, as well as for the setup and teardown of connections to and across the fabric, although these protocols may be implemented on top of Ethernet or Internet Protocol (IP) networks.
Typically, hosts and storage devices (generically, devices) connect to switches through a link between the device and the switch, with a node port (N_port) of the device connected to one end of the link and a fabric port (F_port) of a switch connected to the other end of the link. The N_port describes the capability of the port as an associated device to participate in the fabric topology. Similarly, the F_port describes the capability of the port as an associated switch.
Over time, SANs have become more complex, with fabrics involving multiple switches that use inter-switch links (ISLs) connected to switch ports (E_ports) on the switches. In some SANs, a core group of switches may provide backbone switching for fabric interconnectivity, with few or no devices directly connected to the core switches, while a number of edge switches provide connection points for the devices or devices of the SAN. Additional layers of switches may also exist between the edge switches and the core switches.
Worldwide Names (WWNs) are identifiers that identify a particular FC target. WWNs are assigned to both nodes and ports in an FC fabric. Ports in an FC fabric are assigned Port WWNs (PWWNs) (also known as Worldwide Port Names or WWPNs). Like all WWNs, PWWNs must be unique in a fabric. This assignment is typically done by the manufacturer as part of the manufacturing process.
One problem that current SANs are faced with is the management of PWWNs in a fabric. Zoning in most cases uses PWWNs. Storage arrays are provisioned based on PWWNs. Provisioning of a fabric is currently difficult to plan ahead, and is usually done after the arrival of a server that needs to be connected to the fabric. In addition, if a server connected to a fabric fails, replacing the failed server is quite difficult, and requires many steps, including updating Boot LUN (Logical Unit) zones, fabric zones, and LUN masks. Other advanced fabric features, such as Quality of Service (QoS) require WWNs, including PWWNs.
For example, to attach a server to a fabric today, a fabric wide configuration change is required to add a server, and the process of adding the server requires several steps. The storage administrator must (1) find out the WWN of the host bus adapter (HBA) where the server will be attached; and (2) add LUN masking based on the HBA WWN. The SAN administrator must (1) select a switch port; (2) find out the HBA WWN; (3) create a Boot LUN zone for the HBA WWN; (4) create a zone with the target device; (5) enable zoning; and (6) define device connection control (DCC) policies, QoS, Traffic Isolation (TI) zones, etc.
Fabric administrators have desired a way to pre-provision fabrics, allowing replacement and addition of servers easily, avoiding the difficulties outlined above.